The invention relates to methods and devices for occluding hollow organs in a subject, for example by inducing thrombotic, vasospastic and/or fibrotic occlusion of blood vessels. The invention also relates to methods and devices for increasing the lumen diameter of hollow organs.
It is sometimes therapeutically desirable to occlude blood flow in one or more blood vessels of a human or animal subject. This circumstance may arise in a variety of clinical conditions, such as an acute bleeding episode. Such bleeding may occur from any organ after trauma, or may result from a variety of pathologic conditions such as ulcers, tumors, diverticulitis, portal hypertension, or postpartum hemorrhage.
In many such situations, an invasive surgical approach may be attempted. For example, after pelvic or abdominal trauma, a surgeon may perform open or laparoscopic surgery. The source or sources of bleeding may be identified, cauterized or ligated. However, surgical procedures carry substantial morbidity and mortality rates. There is often an emergent need to control bleeding in order to save the life of the subject, and the subject may expire during the time needed to prepare an operating suite, induce anesthesia, and perform the procedure. In addition, open surgery adds substantial additional stress for the subject.
Accordingly, health care practitioners have sought a more rapid and/or less invasive means of controlling bleeding. For example, a practitioner may access the interior of the subject""s blood vessels by inserting a catheter via a percutaneous approach. A variety of sclerosing or embolic agents may be injected through the catheter, such as ethanol, microfibrillar collagen, Gelfoam, silastic beads, polyvinyl alcohol foam, or polymer resins. The use of some of these agents are described in U.S. Pat. Nos. 5,580,568; 5,667,767; and 6,059,766; Vedantham, et al., Am. J. Obstet. Gynecol. 176: 938-948, 1997; and Imembo, Diverticular Disease of the Colon, Sabiston: Textbook of Surgery, 15th ed., page 987, (copyright) 1997 W. B. Saunders Company. Other percutaneous alternatives include blood coagulation by endovascular delivery of local heat, either by laser or an electrical heating coil, for example, as described in U.S. Pat. Nos. 4,735,201 and 5,851,206.
In addition to control of bleeding, it also may be therapeutically desirable to induce thrombosis in pathologic vascular conditions such as aneurysms, arteriovenous malformations, and arteriovenous shunts, for example as described in U.S. Pat. Nos. 5,122,136; 5,354,295; and 5,894,022; O""Reilly et al., Radiology 171: 471-474, 1989; Kinugasa et al, J. Neurosurg. 77: 501-507, 1992; Taki et al., J. Neurosurg. 77: 37-42 1992; and Takebayashi et al., J. Urol. 159: 696-701, 1998. Blood vessels supplying a tumor represent another target for therapeutic thrombosis; see, for example, U.S. Pat. Nos. 6,093,399 and 6,015,541; and Castaneda-Zuniga, et al., Vascular Embolotherapy, in Interventional Radiology, Part 1, 1: 9-32, Williams and Wilkins, 1992. Such thrombosis may limit tumor growth or metastatic potential by reducing its blood supply.
In addition to blood vessels, it may also be therapeutically desirable to occlude the lumen of other hollow organs. For example, ligation or occlusion of the fallopian tubes of a female subject or the vas deferens of a male subject may provide effective contraception.
Radiofrequency energy has been used to occlude blood vessels, as described in U.S. Pat. No. 5,743,905; to treat vascular aneurysms, as described in U.S. Pat. No. 5,122,136, and to occlude other hollow organs such as fallopian tubes, as described in U.S. Pat. No. 5,556,396. However, energy delivery to the inner wall of the vessel be imprecise, due to a failure of the electrode to conform optimally to the inner wall. Much of the electrode may not be in contact with the inner wall, but instead remains in the lumen. Instead of being delivered to the vascular wall, energy is dissipated into the blood stream. Thus, the vascular tissue may be incompletely cauterized, or alternatively, may be perforated by excessive energy delivery at an isolated contact point.
In addition to occluding lumens of hollow organs, under some clinical circumstances it may be therapeutically desirable to increase lumen diameter. For example, it may be desirable to reduce a stricture or stenosis in a bronchus, esophagus, a segment of intestine, or a blood vessel. In arteries, it may be desirable to reduce a stenosis that reduces blood supply to an organ, for example, a stenosis in a coronary artery that reduces blood supply to the working heart muscle. Moreover, it may be desirable to reduce a restenotic lesion, that is, a stricture or stenosis in a hollow organ that has recurred at least once after a procedure that reduced the severity of the stricture or stenosis. For example, an artery may develop a restenotic lesion after a successful angioplasty procedure at the site of an atherosclerotic stenosis. Such restenotic lesions may develop even when a stent is placed after angioplasty to prop open the vessel. When arterial restenosis occurs after stent placement, it is referred to as in-stent restenosis. Current therapeutic options for in-stent restenosis are limited, and surgery is often required.
Disclosed herein are several specific examples of a device for delivering electrical energy, such as radiofrequency energy, to the walls of a body lumen using a nonconductive catheter. A conductive member capable of conducting an electrical signal is contained within the catheter, and the conductive member is movable between a non-deployed position within the catheter, and a deployed position in which the conductive member is advanced longitudinally through and out of the catheter, wherein the conductive member conforms to the walls of the lumen when the conductive member is in the deployed position.
In some examples, the conductive member in the non-deployed position slides within the catheter, but in the deployed position it assumes a preformed envelope external to the catheter in which the envelope tapers towards both its ends. In particular examples, the catheter in the non-deployed position is linear and non-helical, but in the deployed position is a helix. The helix has an enlarged central diameter that is greater than a proximal diameter of the helix where it emerges from the catheter, and is greater than a distal diameter of the helix at a distal end of the conductive member. In some embodiments, the catheter has a side port through which the conductive member is advanced, which is particularly helpful when the catheter is being introduced into some aneurysms that evaginate from the wall of the blood vessel.
Some of the disclosed examples have an expandable distal end that is retracted, or collapsed into a compact configuration, in the non-deployed position and is expanded in the deployed position. The expandable distal end can assume the form of a plurality of struts that extend longitudinally with respect to the conductive member, and the struts are attached to the conductive member such that longitudinal movement of the conductive member moves the struts between the retracted and expanded positions. For example, the struts are attached at a first end to the conductive member and are fixed at a second end around the conductive member, such that longitudinal movement of the conductive member (for example retraction of the conductive member toward the sheath) forces the struts into the expanded position. The device can include a sheath around the catheter, to which the proximal end of the struts is attached. Then as the distal end of the conductive member is pulled toward the sheath, the struts are compressed and expand to the deployed position in contact with the wall of the lumen.
Some embodiments of the device also include an expandable cuff around the catheter proximal to the expandable member when the expandable member is in the deployed position. Alternatively, expandable cuffs can be provided both distal and proximal to the expandable member, to effectively isolate the expandable member when the electrical energy is supplied to the wall of the lumen (for example, when the device is used to open a vascular occlusion, as in a coronary artery).
In yet another example of the device, the conductive member is an electrically conductive biocompatible liquid, for example a hypertonic liquid, such as hypertonic saline. The catheter is provided with a plurality of ports through which the liquid is deployed to contact the wall of the lumen. When the ports are arranged peripherally around the catheter near the distal tip of the catheter, pressurized expulsion of the conductive liquid can occur as an electrical current is applied through the liquid to the wall of the lumen. The device can further include a source of the biocompatible conductive liquid in communication with the catheter, a pressure source capable of selectively moving the liquid through the catheter, and a source of electrical energy (such as radiofrequency energy) selectively in contact with the liquid.
In other particular non-limiting examples, the device is a nonconductive flexible catheter for introduction into the lumen of a blood vessel, wherein the catheter has a side port in the catheter wall. A conductive wire extends through the catheter, and is made of a memory material such that the wire is non-helical when the conductive wire is in the catheter, but it assumes a helical shape when the wire is advanced out of the catheter through the side port. The wire conforms to the walls of the lumen when the conductive member is in the deployed position, for example assuming an envelope (circumscribing the overall shape of the deployed wire) that tapers toward both ends of the helix, to help conform, for example, to a shape of an aneurysm. The wire can be selectively connected to a source of energy (such as radiofrequency energy) to deliver a signal of a pre-selected intensity for a pre-selected period of time to occlude the aneurysm.
In another particular non-limiting example, a device for delivering electrical energy to a wall of a body lumen includes a non-conductive catheter for introduction into a body lumen, and a conductive wire that extends through the catheter. The wire has a proximal portion that can slide through the catheter for advancing the wire through the catheter, and a distal portion which has a radially expandable member that contacts the wall of the lumen. The expandable member may be, for example, a plurality of longitudinally extending struts that are located at the distal portion of the wire. The struts are radially expanded by longitudinal movement of the wire, with the expandable member in the retracted position, until the expandable member emerges from the catheter. Once the expandable member has emerged from the catheter, it can selectively be expanded in position so that the struts contact the wall of the lumen. In certain embodiments, the expandable member can include longitudinally adjacent first and second (or more) expandable members.
The struts may be arranged to extend longitudinally along the conductive wire, with a first end attached to the conductive wire and a second end attached to a fixation member that is selectively movable relative to the wire. Relative movement between the conductive wire and fixation member retracts and expands the struts. For example, the fixation member may be a sheath or ring around the conductive wire, and the second ends of the struts are attached to the sheath or ring. When the distal ends of the struts are attached to the movable wire, slight retraction of the wire into the catheter through the sheath or ring forces portions of the struts intermediate their opposite ends outwardly away from the longitudinal axis of the wire. The catheter can be a blood vessel catheter, and the struts are expanded once the catheter has been introduced into the blood vessel.
In another specific non-limiting example of a device for delivering electrical energy to a wall of a body lumen, the catheter includes a plurality of fluid orifices that communicate with a catheter lumen. A source of biocompatible conductive liquid selectively communicates with the catheter lumen, and a pressure source selectively moves the conductive liquid though the catheter lumen and out of the fluid orifices into contact with the wall of the body lumen. A source of electrical energy selectively energizes the liquid in the catheter to conduct electrical energy through the liquid as it is moved out of the fluid orifices. The liquid conforms to the walls of the lumen as it is propelled under pressure from the catheter, to precisely deliver the electrical energy to the lumen wall.
The disclosed embodiments also include a method of applying electrical energy to a wall of a body lumen, by introducing a non-conductive catheter into the body lumen, such as a blood vessel (including an aneurysm) or hollow viscus (such as the esophagus). A conductive member is advanced longitudinally through the catheter until it emerges from the catheter, and assumes a shape that contacts the walls of the body lumen. For example, the conductive member is non-helical inside the catheter, but it is made of a memory material that assumes a helical shape after it emerges from the catheter. The helix has an envelope (outline) that tapers toward both its ends, from a relatively enlarged center diameter. In particular embodiments, the conductive member is advanced out of the catheter through a side port in the catheter, and the lumen is an aneurysm lumen. Electrical energy is supplied to the conductive member to, in turn, apply the electrical energy (such as radiofrequency energy) to the wall of the body lumen, which can obliterate the lumen (for example, to treat an aneurysm).
In yet other embodiments of the method, the conductive member includes a distal portion (such as a plurality of longitudinally extending struts) that expands to contact the wall of the lumen. In a retracted position the struts slide through the catheter, but in the expanded position they contact the wall of the lumen. The struts are moved between the retracted and expanded position by longitudinal movement of the conductive member through the catheter.
In other embodiments of the method, the conductive member is a biocompatible conductive liquid that is forced out of the catheter into contact with the walls of the body lumen, as electrical energy is supplied to the liquid, to deliver the energy (such as radiofrequency energy) to the wall of the lumen.